1. Field of the Invention
The invention generally relates to hand tools used in building construction.
2. Description of the Related Art
In drywall installation used in building construction, the drywall must be nailed to its supporting structure to secure the drywall in place. Nails are driven with a hammer deeper than flush with the surrounding surface thereby producing nail indents in the drywall. Then a joint compound, often called “mud,” is spread over the nail indents with a taping knife to cover them. Using the taping knife to wipe the wet mud across the nail indents also makes the now covered nail indents flat with the surround surface of the drywall. The procedure requires two different tools—a hammer and a taping knife.
When working on a section of drywall, the installer generally must use the two tools in sequence and have them ready at each work site. The work is manual labor intensive and does not lend itself to automation. It is especially strenuous work because the installer must perform many movements with his or her arms extended.
One can use industrial engineering techniques to measure the work involved by separating the different tasks. In the prior art the tasks are:
1. Locate hammer.
2. Lift hammer to nail location.
3. Pound in nail with hammer.
4. Put down hammer.
5. Locate taping knife.
6. Lift taping knife to nail location.
7. Apply mud with taping knife.
8. Put down taping knife.
Others have tried to better this process. Two examples are disclosed in U.S. Pat. No. 4,620,369 by Gerken and U.S. Pat. Pub. No. 2008/0047074 A1 by Rosso et al. These references disclose a taping knife with an integral hammer. In both references, the striking surface is at the end of the handle opposite the blade. They improve the prior art by reducing the amount of work involved. The analysis is as follows:
1. Locate knife/hammer.
2. Lift knife/hammer to nail location.
3. Pound in nail with hammer.
4. Turn knife/hammer around using both hands.
5. Apply mud with knife.
6. Put down taping knife/hammer.
Although there are fewer work tasks, these references have some disadvantages. First, the hammer must be swung like a club at the nail using the lightest end of the tool. This is inefficient and uncomfortable. Another way to use them is to jab the nail with the butt end of the handle like a dagger. The user's hand surrounds the handle. Therefore, if the user misses the nail, the nail will injure the user's hand. In both references, the user must rotate the tool end over end to use the opposite side. Using both hands can be dangerous if one is working on a ladder or scaffold, and requires coordinated work with both hands instead of one.
What is needed, therefore, is a taping knife with a hammer that positions the hammer striking portion perpendicular to the handle and aligned with the heaviest part of the tool.